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Abstract #18975 Published in IGR 3-1
Evaluation of short-term increased intraocular pressure on flash- and pattern-generated electroretinograms of dogs
Hamor RE; Gerding PA Jr; Ramsey DT; Whiteley HE; Benson GJ; Schaeffer DJAmerican Journal of Veterinary Research 2000; 61: 1087-1091
OBJECTIVE: To determine the electrodiagnostic and histologic response of short-term increases of intraocular pressure (IOP) on transient pattern electroretinograms (PERG) and flash electroretinograms (FERG) in the eyes of dogs. ANIMALS: Eight healthy mixed-breed dogs. PROCEDURE: Transient PERG and FERG waveforms were recorded from dogs (while anesthetized) as IOP was increased from baseline (7-19 mmHg) to 90 mmHg. One hundred mean PERG responses and a single FERG response were recorded at each step during three recording sessions. Globes of each dog were enucleated after euthanasia on post-treatment Day 7 and evaluated by a pathologist. RESULTS: Increases in spatial frequency resulted in decreased amplitudes of N2 (second negative PERG peak). Increases in IOP resulted in decreases in all three PERG waveforms and the FERG waveform. All values began to return to baseline after short-term increases in IOP on Day 0, and waveforms were not significantly different on post-treatment Days 3 and 7 CONCLUSIONS: The data suggest that short-term increases in IOP affect PERG and FERG waveforms, and PERG waveforms are more sensitive to increases in IOP. Differences were not detected between treated and control eyes on histologic examination. Further studies are necessary to determine at what IOP permanent damage to ganglion and photoreceptor cells will develop and whether PERG is a reliable clinical diagnostic technique for use in dogs to reveal retinal damage that is secondary to increased IOP prior to changes in waveforms generated by FERG in dogs.
Dr R.E. Hamor, Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana, IL 61802, USA
Classification:
3.3 Immunohistochemistry (Part of: 3 Laboratory methods)